The present invention relates to a compound teeth type gas compressor.
U.S. Pat. No. 3,574,491 discloses a compound teeth type rotary machine for transport of liquids or for compression or expansion of gases. The machine comprises a housing defining a cavity and having an inlet port and an outlet port, a pair of mating gears rotatably accommodated in the housing, each gear having two kinds of teeth which are of different size and have a common pitch circle, and a pair of shafts each rotatably journaled in the housing and each secured to one of the gears. According to the known rotary machine, torque transmitting means are mounted on the shafts externally of the housing for rotating the pair of mating gear, and the torque transmitting means are arranged to maintain the pair of gears out of metallic contact with each other during rotating. This prior art rotary machine has a relatively large size and a complex structure because of the additional torque transmitting means. In addition, since the gears are out of metallic contact with each other during rotating, and especially each of teeth of larger size is of a configuration with a circular pitch as a unit for engagement (one tooth for one gullet), a large quantity of reflux occurs during the liquid transmission and the efficiency of the transmission becomes very low. Therefore said rotary machine basically does not have the function of gas compression and expansion, and is difficult to be applied in industry.
An object of the present invention is to provide a compound teeth type gas compressor with less noise, small size, simple configuration and reduced or avoidable gas charging caused by gas reflux.
This object is achieved by a compound teeth type gas compressor according to the present invention, which comprises a housing with an upper end cover and a lower end cover mounted on both sides of the housing for constituting a seal cavity, a pair of meshing gears rotatably accommodated in the cavity, each gear having two kinds of teeth which are of different size and have a common pitch circle, an inlet port and an outlet port, an intake chamber and a discharge chamber positioned respectively on the sides of the inlet port and the outlet port in the cavity, wherein the gears are unidirectionally rotated, one of them is a driving gear having larger teeth, the other is a driven gear having larger gullets engaged with the larger teeth, the larger teeth and the larger gullets are formed with asymmetric shapes, and, as viewed in the rotation directions of the gears, their front flank profile curves are designed to achieve a transmission of a constant angular velocity ratio while their rear flank profile curves are designed to be in conjugate contact with each other from the beginning to the end of touching.
According to a further development of the present invention, the outlet port is arranged in said end cover and a clearance gas discharging groove is arranged on the gear having the larger gullets for connecting the larger gullets with the outlet port.
The compound teeth type gas compressor according to the present invention has the following advantages:
1. The transmitting mechanism and the gas compressing mechanism thereof are unified with a very simple structure. The whole compressor has only five major components: a pair of meshing gears, a housing, an upper end cover and a lower end cover, and thus has a light weight, a small size and a low cost.
2. The dynamic balancing performance thereof is good. The compressor has not any crank or eccentric mechanism, and has a stable movement and a small vibration. No inlet and outlet valves exist, and the compressor has a low noise.
3. The asymmetric arrangement of the flank profiles and the disposition of the clearance gas discharging groove can achieve a small clearance volume, avoid the gas charging caused by gas reflux, and reduce mechanical wear, thereby increasing the energy efficiency ratio and the volumetric efficiency.